1. Technical Field of the Invention
The present invention relates to disk formatters, disk drives and related methods.
2. Description of Related Art
As is known, many varieties of disk drives, such as magnetic disk drives are used to provide data storage for a host device, either directly, or through a network such as a storage area network (SAN) or network attached storage (NAS). Typical host devices include stand alone computer systems such as a desktop or laptop computer, enterprise storage devices such as servers, storage arrays such as a redundant array of independent disks (RAID) arrays, storage routers, storage switches and storage directors, and other consumer devices such as video game systems and digital video recorders. These devices provide high storage capacity in a cost effective manner.
As a magnetic hard drive is manufactured it is formatted at the factory. The formatting process typically includes at least one stage where data is read to the drive in a physical mode corresponding to the physical parameters of the drive. For example, a disk drive with 1024 cylinders, 256 heads and 63 sectors per track has (1024)×(256)×(63)=16,515,072 sectors. Each sector can be physically addressed based on its corresponding cylinder, head and sector number, e.g. cylinder 437, head 199, sector 12. A test pattern is written to, and read from, each disk sector in physical mode to determine which sectors of the disk are good and are available for storage, and which sectors are bad and should not be used.
The sectors of the disk are assigned a logical block address (LBA) that translates the physical sectors of the drive into a linear, sequentially numbered set of blocks that includes the good sectors and excludes the bad sectors. These LBA addresses are used in communicating with a host device in host interface protocols such as small computer system interface (SCSI) or serial advanced technology attachment (SATA), in order to write to or read data from the drive. In formatting the drive at the factory, the drive is completely rewritten in logical mode, using the assigned LBAs, for access by the user once the drive is installed and coupled to a host device. When a user of a host device reads data from the drive, he reads the data in logical mode. If a sector that was written in physical address mode were attempted to be read by a user in logical mode, the user would receive errors related to the block address.
A sizable market has developed for these devices and the price per unit of storage has steadily dropped. Modern host devices are provided with greater storage capacity at reduced cost, compared with devices that where manufactured a few years earlier. The need exists for provide hard drives that can be manufactured efficiently on a mass scale with reduced cost.